[time-nuts] Temperature effect on delay of FatPPS :)

[Hal Murray]

I'm putting some data collection toys back together.

I've got a TAPR TICC watching a couple of PPS signals.

The clock for the TICC comes from a HP 5334B with the good crystal option.  
It's not right-on in frequency, but there is no control voltage that might be 
wiggling around so it should be stable.

This setup is half backwards.  I'm using the PPS to calibrate the frequency of 
the TICC reference clock, then assuming the reference clock is short term 
stable and using it to examine the short term characteristics of the PPS 
signals.

The green line is the PPS signal from a Sure demo board with a SKG16B GPS chip.
  http://www.leapsecond.com/pages/MG1613S/

The wander in the green line is a combination of warmup and temperature.  The 
5334B was off for several months.  This graph starts on day 18.  The wiggles 
are easy to see on an expanded scale but that blows the FatPPS signal off 
scale.  The daily temperature swings are roughly the same size as the daily 
drift.  (Another graph for another message...)

The PPS signals are connected via clip leads to handy places.  One of those 
was after a FatPPS.  That signal is upside down so the TICC is triggering on 
the trailing edge.  No problem, I thought, I can just fix that up when 
graphing things.  :)

After I saw the initial results, I put a temperature probe on the FatPPS.  The 
spike at 18 hours is the direct morning sun peeking through the houses and 
trees across the street.



-- 
These are my opinions.  I hate spam.

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